Expansion shell with swaged connecting strap



N. H. SIEGEL 3,248,998

EXPANSION SHELL WITH SWAGED CONNECTING STRAP May 3, 1966 Filed March 20, 1964 3 R. H m F m mm F H M Y 2 I 2 9 Nil 2 m; M s g 8 W 8 {8 m 5 0 v Y 1 n B 9 a 6 4 Fl.

L m M7 Lv F i J G U? FIG.9

United States Patent 3,248,998 EXPANSION SHELL WITH SWAGED CONNEETING STRAP Norman II. Siegel, Syracuse, N.Y., assignor, by mesne assignments, to The Eastern Company, Syracuse, N.Y., a corporation of Connecticut Filed Mar. 20, 1964, Ser. No. 353,547 4 Claims. (CI. 8587) This invention relates to expansion shells of the two part shell type utilizing a connecting strap.

In a patent to Dickow 3,181,414, there is disclosed a mine roof expansion shell assembly, wherein two like shell members in the form of malleable castings, are tied together by a U strap formed from sheet metal. The attachment of such strap at its ends to the respective shell members has heretofore been accomplished by providing the strap with dovetailed ends, which are held in complemental recesses cast in the respective members, the recesses being bound by ears which being malleable, are readily bent over the dovetail ends of the strap to secure the same in position. The formation of straps, with dovetailed ends by punch press operation from sheet stock has resulted in considerable waste stock, since the Width of sheet material required for each strap has been governed by the overall width of the dovetailed end, each strap being of uniform thickness including its dovetail ends, and being struck from sheet material of uniform thickness.

The present invention is directed to the forming of dovetailed ends upon a strap of uniform thickness and width, whereby wastage of material is entirely eliminated. The dovetailed end is produced by swaging the strap ends into a channel section having a thin triangular web and diverging side flanges, which thus expands the overall width of the strap to form the dovetail.- The invention is further also directed to the employment of such straps in combination with shell members having the complemental dovetail recesses heretofore provided, the dovetailed ends being held in their respective shell member recesses with the channel web seated upon the recess bottom, by the ears swaged over the diverging side flanges. The channel sectioned dovetailed ends and particularly the central web portions thereof are forced into flat engagement with the recess bottom. The straps, thus formed without waste, and particularly the dovetailed ends thereof are secured more tightly in their respective recesses, and any transverse buckling of the ends due to lateral pressure of the ears formed over the flanges, tends to thrust dovetailed end flat against the recess bottom of the shell members.

The above and other novel features of the invention will appear more fully hereinafter from the following detailed description when taken in conjunction with the accompanying drawings. It is expressly understood that the drawings are employed for purposes of illustration only and are not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawings wherein like reference numerals indicate like parts:

FIGURE 1 is a front elevational view of a wedge, and two part shell joined by a strap embodying the invention;

FIGURE 2 is a top plan view of such a shell;

FIGURE 3 is a side elevational view of the wedge and shell, with a half shown in longitudinal section;

FIGURE 4 is an elevational view of a shell element before assembly;

FIGURE 5 is a sectional view taken on the line 5-5 of FIGURE 4;

FIGURE 6 is an end view of the shell element;

"Ice

FIGURE 7 is a view of a strap element ready for having its ends formed into dovetails;

FIGURE 8 is a view of a strap after having its ends formed into dovetails;

FIGURE 9 is an end view of the strap of FIGURE 8;

FIGURE 10 is an enlarged sectional view of the strap end taken on the line 1010 of FIGURE 8;

FIGURE 11 is a fragmentary enlarged longitudinal sectional view of the strap end taken on the line 1111 of FIGURE 8;

FIGURE 12 is an enlarged fragmentary sectional view of the strap end swaged in place upon a shell element;

FIGURE 13 is a sectional view taken on the line 1313 of FIGURE 12;

FIGURE 14 is a plan view of section of strip sheet steel showing the wasteful manner of punching straps with preformed dovetail ends therefrom, and

FIGURE 15 is a plan and edge view of such strap as cut from the sheet material of FIGURE 14.

Referring to the drawings and particularly FIGURES 1-3 there is shown an expansion shell assembly of the type shown in Patent No. 3,181,414, wherein the shell com-prises a pair of llike shell members 20, each having segments 22 and 24 disposed substantially at right angles to each other and integrally connected together at their lower ends as at 26. Each segment has an internal camming surface 28, and external gripping teeth 30, and a wedge 32 having four inclined surfaces 33 adapted to engage the carnming surfaces 28 of the four segments of the two members 20. The wedge 32 is provided wtih wings such as 34 which ride in slots 36 between the adjacent segments 22 and 24 of each member 20. The wedge has a threaded aperture 36 into which the end 38 of a mine roof bolt is threaded. The bolt head 42 is adapted to bear against a plate 44 which in turn will bear against the mine roof, when the expansion shell assembly is expanded into anchoring relation with the mine roof bore in which it is positioned.

In order to secure the shell members 20 together in an assembly about the wedge 32, and to provide initial resistance upon the end of the bolt, to move the wedge downwardly in the assembly, a steel strap 50 of semiresi'lient steel such as cold rolled steel is provided, the dovetailed ends 52 and 54 of which are anchored in recesses 56 in the upper ends of the segments 22 of each of the shell members 20. Such ends are held in position by swaging the cars 58, 59 over the dovetailed ends.

Heretofore, strap members such as 60 were punched from coils of sheet steel of a width equal to or greater than the length of the straps punched; the sheet metal 62 having a width as generally indicated in FIGURE 14, and the strap members were punched to shape with dovetailed ends 64, leaving recesses 66 in the strip stock, and intervening waste material 6 8 of a width approximately that of the width of the central portion of the strap. Such practice was wasteful, utilizing a length of strip stock equal to twice the width of the central body portion 70 of each strap formed. Furthermore when the d0ve tailed ends 64 thus formed were located in the recesses 56, and the ears swaged in place, there was a tendency to buckle the dovetailed ends transversely thereof from the lateral pressure exerted on the side edges 72 of the dovetailed ends 64. Once buckled, the dove-tailed end was prone to further buckling and pullout.

In order to provide a strap without waste, as resulted from the prior procedure as indicated by FIGURES 14 and 15, the present invention is directed to forming the strap from rectangular sections of stock such as shown in FIGURE 7, the same being of uniform width and thickness throughout it length, and of the length desired for the strap. In order to form dovetailed ends upon the section 80 from a strap of uniform width, the ends are swaged centrally as at 82 to thin and flow the metal, whereby the side edges 84 and 86 of the metal are formed outwardly tot form the dovetailed ends. As can be seen from FIGURES and 11, the result is a shallow channel shaped section having a web portion 83 of generally isosceles triangular shape, and side flanges 90 and 92 of the thickness of the section 80 from which the strap is formed.

Each of the dovetailed ends, thus formed is laid in the corresponding recess 56 of a shell member with the triangular web portion seated on the recess bottom surface 57, and the cars 58 and 59, are then swaged over the flanges 90 and 92, in the manner shown in FIGURES 12 and 13. It can be seen that lateral pressure of the ears upon the side edges 91 and 93 of the flanges 90 and 92, when swaged to the positions shown in FIGURES 12 and 13 can only result in squeezing the channel sectioned dovetailed end, and since the web portion 88 of the channel end lies against the flat surface 57 of the recess 56 any lateral squeezing of the dovetail end of the strap tends to force the web portion 88 inwardly against the surface 57 of the recess 56. In other words, any tendency of the dovetailed end to buckle, can only be in a direction inwardly and against the surface 57 on which the end is seated and which resists such buckling.

In the case of the dovetailed end of the straps heretofore employed the buckling of the dovetail end could only occur in a direction outwardly away from the flat bottom surface 57 of the recess in the shell member, and while such buckling could be resisted during the swaging operation by temporary means pressing against the dovetailed end, to hold it seated in the recess, but as soon as such temporary means was removed, the resistance to outward buckling was gone.

A slight outward buckling efiect resulting during assembly by side pressure from the ears, results in a dovetailed end which may buckle further on tension being applied with resultant pull out.

While a single form of the invention has been referred to, it will be understood that the invention is not limited thereto. As various changes in the construction and arrangement may be made without departing from the spirit of the invention, as will be apparent to those skilled in the art, reference will be to the appended claims for a definition of the limits of the invention.

What is claimed is:

'1. A strap for use in connecting the upper ends of two cast members of an expansion shell, said strap comprising an elongated strip of thin resilient sheet metal 'of uniform width and thickness throughout the central portion of its length and of uniform cross sectional area throughout its entire length, the opposite ends of said strap being swaged to form widened ends and said ends being channel-like in cross-section and having edgewise side flanges of a height equal to the thickness of the ,central portion of the strip, and a web portion of a thickness substantially less than the thickness of said central portion, one surface of said web portion being co-planar with the adjacent surface of one side ofthe central portion.

2. A strap for use in connecting the upper ends of two cast members of an expansion shell, said strap comprising an elongated strip of thin resilient sheet metal of uniform width and thickness throughout the central portion of its length and of uniform cross sectional area throughout its entire length, the opposite ends of said strap being swaged to form dovetailed ends and said ends being of gradually enlarging width, and terminating in substantially transverse ends, each of the dovetailed ends being channel-like in cross-section, and having diverging side flanges of .a height equal to the thickness of the central portion of the strip, and a web portion of triangular shape of a substantially uniform thickness substantially less than the thickness of said central portion, one surface of said web portion being co planar with the adjacent surface of one side of the central portion.

3. An expansion shell for mine roof support and the like com-prising two like shell segments of malleable iron, each of said shell segments having external arcuate gripping teeth and internal wedging surfaces, and being thicker at one end than the other, and each of said shell segments having a flat bottom dovetail shaped recess in its outer surface at the said other end, and a U-shaped strap comprising an elongate strip of resilient sheet metal having a swaged dovetail configuration at either end complemental to the recesses of said segments, and seated therein, said dovetail ends being of channel section configuration with the web portions seated against the flat bottom of said recess, and integral fingers integral with said shell segments disposed on the opposite sides of each of said recesses, said fingers being formed over the respective side flanges of said swaged channel section dovetailed ends.

4. An expansion shell for mine roof support and the like comprising two like shell segments of malleable iron, each of said shell segments having external arcuate gripping teeth and internal wedgin-g surfaces, and being thicker at one end than the other, and each of said shell segments having a flat bottom dovetail shaped recess in its outer surface at the said other end, and a U shaped strap comprising an elongate strip of resilient sheet metal of uniform section in its central portion, and having a swaged dovetail configuration at its opposite ends complemental to the recesses of said segments, and seated therein, said dovetail ends being of widening channel section configuration with a substantially triangular web and diverging side flanges, the web portions being seated against the flat bottom of the respective said recesses, and integral fingers integral with said shell segments disposed on the opposite sides of each of said recesses, said fingers being formed over the respective side flanges of said channel section dovetailed ends whereby to provide a secure connection between the strap ends and the shell segments.

References Cited by the Examiner UNITED STATES PATENTS 380,413 4/1888 Webster 78-62 1,746,963 2/ 1930 Pleister et al 85 3,181,414 5/1965 Dickow 85--75 EDWARD C. ALLEN, Primary Examiner. 

4. AN EXPANSION SHELL FOR MINE ROOF SUPPORT AND THE LIKE COMPRISING TWO LIKE SHELL SEGMENTS OF MALLEABLE IRON, EACH OF SAID SHELL SEGMENTS HAVING EXTERNAL ARCUATE GRIPPING TEETH AND INTERNAL WEDGING SURFACES, AND BEING THICKER AT ONE END THAN THE OTHER, AND EACH OF SAID SHELL SEGMENTS HAVING A FLAT BOTTOM DOVETAIL SHAPED RECESS IN ITS OUTER SURFACE AT THE SAID OTHER END, AND A U SHAPED STRAP COMPRISING AN ELONGATE STRIP OF RESILIENT SHEET METAL OF UNIFORM SECTION IN ITS CENTRAL PORTION, AND HAVING A SWAGED DOVETAIL CONFIGURATION AT ITS OPPOSITE ENDS COMPLEMENTAL TO THE RECESSES OF SAID SEGMENTS, AND SEATED THEREIN, SAID DOVETAIL ENDS BEING OF WIDENING CHANNEL SECTION CONFIGURATION WITH A SUBSTANTIALLY TRIANGULAR WEB AND DIVERGING SIDE FLANGES, THE WEB PORTIONS BEING SEATED AGAINST THE FLAT BOTTOM OF THE RESPECTIVE SAID RECESSES, AND INTEGRAL FINGERS INTEGRAL WITH SAID SHELL SEGMENTS DISPOSED ON THE OPPOSITE SIDES OF EACH OF SAID RECESSES, SAID FINGERS BEING FORMED OVER THE RESPECTIVE SIDE FLANGES OF SAID CHANNEL SECTION DOVETAILED ENDS WHEREBY TO PROVIDE A SECURE CONNECTION BETWEEN THE STRAP ENDS AND THE SHELL SEGMENTS. 